Method of bending pipe



Dec. 22, 1942. CARL 2,305,951

METHOD OF BENDING PIPE Filed May 27, 1941 Z /7 w 6 Q-w 2 INVENTOR. NH THHN ARL Patented Dec. 22, 1942. 2,305,951

UNITED STATES PATENT OFFICE I mnrnon 3 23a; rrrn Nathan Carl, Brooklyn, N. Y. Application May 27, 1941, Serial No. 395,325

1 Claim. (01. 153-40) This invention is a method for bending pipe in Figure 1 show a central section through the such manner that the pipe will not be crushed or mandrel and the associated former with a pipe in distorted during the bending operation. but will the process of bending shown partially in central retain its substantially normal cross section at section and partiallyin elevation. the bend. s Figure 2 is a section through the pipe showing. I am aware of Patent No. 2,119,875, issued on one end of the mandrel and with the connection June '7, 1938, to my father, Louis Carl. In the between the mandrel and the follower in section. pipe bending method and apparatus of that pat- This view is taken in the plane of the line 2-4 of ent there is disclosed a mandrel composed of a Figure 1. succession of units of I-beam cross section suc- Referring'to Figs. 1 and 2 of the drawing, I cessively secured to one another by interfitting designates an appropriate former mounted to rolinks, rigid with the respective units insuch mantate on a shaft 2. The former may be mechanner as'to, permit cross axial flexing of the manically rotated through gears or other appropriate drel while all Of the units of the mandrel are connections with any suitable prime mover, but, locked together against relative rotation. When for the purpose of illustration, I have shown the a pipe is held against longitudinal movement and rotating means in the form of a manually operbent about a suitable former, the mandrel is able handle 3 of sufiicient len h p y the adapted to be rotated and simultaneously moved necessary force. This handle iskeyed to the longitudinally within the pipe to preclude crimpshaft 2 to which the former I is also keyed. The ing of the pipe throughout the bend and to main- 2o pe iphery of e f er s curved t p o e a tain the cross section of the pipe substantially substantially semi-circular channel 4 into which uniform. one-half of the diameter of the pipe P is'adapted The present invention operates in a different to be received. manner and utilizes a far more economical con- Positioned in substantially tan ntial rela i n struction. In contradistinction to my fathers to the base of the channel 4 of the former is a patent, I employ a rigidmandrel composed, in mandrel 5. This mandrel is shown as made up of effect, of a single rigid member to the end o two parts 511 d e p r s 1 and 5b are of which is attached a follower of the same diameter the same external diameter and they are aras the rigid mandrel. The mandrel is adapted to ranged in coaxi l r l i to abut at h Pl n 5 be rotated during the bending operation but is e e t ey ay be t readed t t or w ded or fixed against axial movement, while the follower both as may be desired, o as to become rigid with is secured to theend of the mandrel by a ball and respect to one another and form collectively in socket joint so that, whenthe mandrel is rotated, effect one part. For the purpose of illustration, the follower does not rotate, but simply occupies the sections 5a and 5b are shown as welded at I. the space within the pipe substantially equal to 5 They collectively form a' mandrel of somewhat the normal interior pipe diameter and precludes gre t r length a m rcrushing of the pipe at the point where the bend In the abutting faces of the sections 5a and 5b commences. In further contradistinction to the are formed collectively thesocket 8 of a ball and said prior patent, the present invention consists socket joint. This socket is substantially spherin moving the pipe axially, whereby it is drawn 40 ical and from the base of the socket in the part 5b apast the mandrel and about the former to obtain extends an outwardly tapering Su s ant al y the desired bend., The two methods are wholly frusto conical throat s shaped s to p it of distinct from one another and theapparatus emarticulation of the shank I'll of the ball II which ployed operates in a different way. The present is fitted within the socket 8. structure is much simpler than the prior con- The shank I0 is rigidly secured to a follower l2. struction. These parts may be attached togetherin any suit- Features of the'invention, other than those adable way, but, for the purpose of illustration, the verted to will be apparent from the hereinafter shank Ill is shown as passing through a central detailed description and claims when read in con- Opening in the follower and welded to the follower junction with the accompanying drawing. at ii. The follower I2 is of substantially spher- The accompanying drawing illustrates one pracical section with parallel opposite faces, the ditical embodiment of the invention, but the conameter of the sphere being substantially the same struction therein shown is to be understood as as the diameter of the mandrel 5.

illustrative, only, and not as defining the limits In the rear end of the mandrel 5 is a threaded of the invention.

socket l4 and into this threaded socket is screwed spindle may be rotated in a coun bend to be produced in the pipe may be made at some distance from its end.

To hold the mandrel in proper radial relation with respect to the former, a supporting block I l is provided and this is adapted to straddle the pipe P directly adjacent a plane passing through the axis of the shaft 2 and perpendicular to the axis of the mandrel. This supporting block may besecured in place in any suitable way, butmust be rigid enough to hold the pipe against the former. The pipe is adapted to be clamped to the former by means of a clamp I8 embodying. a yoke l9 secured to the former I and adapted to be tightly forced against the pipe by a set screw 20. The clamp l8 has a semi circular face engaging the pipe and is adapted to embrace one-half the diameter thereof.

When it is desired to bend a pipe in the apparatus asshown, the former is moved into position to bring one face of the yoke l9 into engagement with the supporting block l1, these two contiguous faces then occupying a plane which includes the axis of the shaft 2 and which is perpendicular to the axis of the mandrel. This relation permits a straight pipe to be passed through the clamp I 8 and through the block I! while embracing the follower I2 and the mandrel 5. The pipe is pushed along in a right hand direction until the point of the pipe where the bend is to start reaches said pe pendicular plane.

When the pipe has been brought into this position, the supporting block I! is made rigid in a position for continued contact with the pipe and the set screw 20 is tightened to anchor the.

pipe firmly between the clamp I8 and the former, so that the pipe is rigidly secured to the former at this point which, as stated, is to be the point of the start of the bend.

After these conditions have been obtained, rotation of the shaft I5 is commenced and, while this shaft is rotating and imparting like rotation to the mandrel, the handle 3 is grasped and moved in a counterclockwise direction, drawing with it the pipe P and causing the pipe to be bent about the former as indicated in Figure 1. The bend may be of any angular degree up to approximately 180 degrees. With a greater bend difficulty would be experienced in freeing the pipe from the former after the bend is finished.

During the bending operation the mandrel 5 continues to rotate and holds the pipe in distended position at the point of the start of the bend, so that it cannot crush at this point, where the greatest crushing strain generally occurs. The follower is not locked mandrel and simply occupies a position adjacent the point of greatest crushing strain,1 o as to safeguard the pipe against crushing in this region.

After the pipe has been bent as desired, the clamp is released and the pipe is pulled-free from the former in finished condition.

It will be found when bending pipes in the manner described and through the apparatus shown, that a uniform bend will be obtained and that the interior diameter of the pipe throughout the bend, as well as adjacent thereto, will be substantially uniform.

In the structure, hereinbefore fully explained, the mandrel is rotated, but the follower is not locked for rotation with the mandrel. This clearly distinguishes that form of the invention from my fathers patent wherein all the units which are enclosed within the pipe are rotated with the mandrel while the mandrel as -a whole is longitudinally moved within the pipe during the bending operation. According to the present invention the mandrel does not move axially but this movement is limited to one of rotation.

In the foregoing detailed description I have set forth the invention in its preferred practical form, but the invention will be understood as fully commensurate with the appended claim.

Having thus fully described the invention, what I claim as new and desire to secure by Letters Patent is:

The herein described method which comprises drawing a pipe longitudinally about a former to produce a bend in the pipe, while rotating an axially stationary rigid sizing mandrel within the unbent portion of the pipe adjacent the start of the bend and maintaining a non-rotating sizing follower in stationary position within a bent portion of the pipe adjacent the start of the bend.

NATHAN CARL.

for rotation with the 4 

